Could I get in trouble for posting this on facebook?

[Bob Warnerr]

So, I posted this on facebook

"This 18 yr old Senior is dating my 14 yr old freshman sister. I swear, if he makes 1 wrong move. Let's just say, the internet is a good way to find out someone's address."

One of my friends told me that I could get into trouble for making a "threat", yes, that is what I mean it as, a threat, but technically all it's saying in my distaste for the relationship and that the internet can tell me people's addresses.
I'm 17 and a Junior in highschool. We go to different highschools as well.
Dear Colinc, you and your no life, 42,000 answers can just leave. I am not controlling the relationship nor being a monster about it. I am allowed to have an opinion and a distaste for the relationship if I want. I am not even trying to talk to her to change her mind. So please, go f*** off somewhere else. Thank you